1. Field of the Invention
The present invention generally relates to an image forming apparatus, such as a copier, a printer, a facsimile machine, a multifunction machine including at least two of those functions, etc., a cleaning device used therein, and a process cartridge.
2. Discussion of the Background Art
In general, an electrophotographic image forming apparatus, such as a copier, a printer, a facsimile machine, a multifunction machine including at least two of those functions, etc., includes an image forming unit for forming an electrostatic latent image on an image carrier, and developing the latent image with developer. The developed image (toner image) is then transferred from the image carrier onto a sheet of recording medium, such as paper, overhead projector (OHP) films, and the like, and fixed thereon.
After the image is transferred from the image carrier, a cleaning device including a cleaning blade, or the like, removes any toner remaining on a surface of the image carrier.
A known cleaning device for the image carrier includes a lubricant applicator that applies lubricant onto the surface of the image carrier while a cleaning blade removes any toner remaining on the image carrier after the image is transferred therefrom. Applying lubricant onto the surface of the image carrier can decrease a frictional coefficient of the surface of the image carrier, enhancing removability of the toner while preventing or reducing filming of the image carrier, which means that the toner or the like adheres firmly to the surface of the image carrier. Moreover, when a photoreceptor is used as the image carrier, such an arrangement can reduce scraping of the photoreceptor.
FIG. 1 schematically illustrates an example of one such known image forming unit.
As shown in FIG. 1, the image forming unit includes a photoreceptor 3Z that rotates in a direction indicated by an arrow in FIG. 1 (hereinafter “photoreceptor rotational direction”), a cleaning device 6Z located on the right of the image carrier 3Z, and a developing unit 5Z located on the left of the image carrier 3Z in FIG. 1. The cleaning device 6Z includes a cleaning blade 61Z, a roller-shaped lubricating brush 62Z located downstream from the cleaning blade 61Z, and a doctor blade 66Z located downstream from the lubricating brush 62Z in the photoreceptor rotational direction and contacting the photoreceptor 3Z.
The lubricating brush 62Z scrapes a solid lubricator 64Z and applies the scraped lubricant onto a surface of the photoreceptor 3Z while rotating. Then, the doctor blade 66Z distributes the lubricant on the surface of the photoreceptor 3Z evenly so as to form a uniform lubricant layer thereon. When the lubricant on the surface of the photoreceptor 3Z is excessive, the doctor blade 66Z removes and retains the excessive lubricant.
In the cleaning device 6Z described above, although the cleaning blade 61Z scrapes off the toner remaining on the surface of the photoreceptor 3Z, a small amount of the scraped toner can slip through a gap between the cleaning blade 61Z and the photoreceptor 3Z and reach the lubricating brush 62Z or the doctor blade 66Z. Such toner is then scraped or retained by the lubricating brush 62Z or the doctor blade 66Z.
In the configuration in which the lubricating brush 62Z is located above the cleaning blade 61Z, the toner removed or retained by the lubricating brush 62Z can drop therefrom onto the cleaning blade 61Z. Additionally, it can happen that some of the lubricant scraped from the solid lubricant 64Z fails to be applied to the photoreceptor 3Z but remains on the lubricating brush 62Z (hereinafter “unused lubricant”), and such unused lubricant can drop onto the cleaning blade 61Z as well.